Micro-electrical-mechanical systems (MEMS) devices are currently being developed for a wide variety of applications. A MEMS device generally includes at least one mechanical element, such as a sensor, an actuator, or a resonator, that is formed using a micromachining process that selectively etches away parts of a wafer. The wafer may include added structural layers and may be made of a semiconductor material, such as Silicon. Several devices, such as resonators, filters, capacitors, and switches may be advantageously developed as MEMS devices due to the size, cost, and power consumption advantages afforded therefrom.
Many MEMS devices rely on the piezoelectric effect of one or more layers in the device to mechanically actuate or resonate in order to provide the functionality of the device. One particularly interesting piezoelectric material is the piezoelectric bimorph, in which a first piezoelectric layer having a first set of piezoelectric properties is placed on top of a second piezoelectric layer having a second set of piezoelectric properties. Notably, the piezoelectric properties of the first piezoelectric layer and the second piezoelectric layer are different, such that when the layers are electrically activated, one of the layers may expand or contract more than the other, causing the piezoelectric bimorph to mechanically deform more than would otherwise be possible using a single layer of piezoelectric material.
Although MEMS devices currently exist for a wide variety of applications, many of the devices are difficult to manufacture, provide sub-optimal performance, or are only fit for a single purpose. Accordingly, there is an ongoing need for improved MEMS devices and structures.